The present installation relates to a vaporizer/condenser of the bath type, comprising at least one heat exchange body, having a multitude of flat passages for the countercurrent circulation of two fluids, from one or several distillation columns, in a same direction, and at least one sealed chamber for confining a fluid containing the or each heat exchange body, the confining chamber comprising a central section of generally cylindrical shape along a longitudinal axis, the longitudinal axis of the central section of said or each confinement chamber being substantially orthogonal to the direction of countercurrent circulation of the fluids in the flat passages of the corresponding heat exchange body.
The term xe2x80x9csubstantially orthogonalxe2x80x9d comprises spacings up to 30xc2x0, or 20xc2x0, or preferably 10xc2x0 from strict orthogonality.
It is sometimes necessary to orient the vaporizer so as to facilitate draining of the liquids.
A vaporizer-condenser of this type is known from DE 1152432, in which the confinement chamber is limited in part by the heat exchange body, the liquid bath of the vaporizer being located exclusively outside the confinement element.
The invention is applicable in particular to double column air distillation installations, which is to say with a medium pressure column thermally connected to a low pressure column, provided with vaporizers-condensers of mentioned type.
In such installations for the distillation of air, the liquid oxygen which is in the base of the low pressure column is vaporized in the vaporizer-condenser by heat exchange with gaseous nitrogen from the head of the medium pressure column.
For a given operating pressure of the low pressure column, the temperature difference between the oxygen and the nitrogen rendered necessary by the structure of the vaporizer-condenser dictates the operating pressure of the medium pressure column.
It is therefore desirable that this temperature difference be as small as possible, so as to minimize the expenses connected with the compression of air to be treated injected into the medium pressure column.
The reduction of the temperature difference between the nitrogen and the oxygen requires, to preserve the heat exchange capacity of the vaporizer-condenser, increasing the heat exchange surface in this latter.
A first solution would consist in increasing the height of the heat exchange body of the vaporizer-condenser to increase the heat exchange surface. However, such an increase of height leads to a hydrostatic overpressure in the oxygen passages which tend to increase the temperature difference and which would impede the good operation of the vaporizer-condenser.
Another solution would consist in multiplying the number of passages dedicated to the oxygen and to the nitrogen, for example by increasing the number of the juxtaposed heat exchange blocks which constitute the exchanger body and which operate in parallel in the vaporizer-condenser.
Generally speaking, in double column distillation installations, the low pressure column surmounts the vaporizer-condenser which itself surmounts a medium pressure column. The central section of the sealed chamber of the vaporizer-condenser is thus constituted by a sleeve with a vertical axis of revolution. This sleeve is preferably of the same diameter as the sleeves delimiting the medium pressure and low pressure columns.
The use of the second solution to increase the heat exchange surface in such a distillation installation would thus require having a vaporizer-condenser sleeve of a diameter greater than those of the medium and low pressure columns.
The cost of construction of such an installation would thus be relatively high, particularly because of the large diameter of the sleeve of the vaporizer-condenser and the particular connection pieces to be provided between the sleeve of the vaporizer-condenser and the sleeves of the medium and low pressure columns.
The invention has for its object to solve this problem by providing a vaporizer-condenser of the mentioned type, which can function with reduced temperature differences and which permit particularly building double column air distillation installations that are relatively simple and of low cost to construct.
To this end, the invention has for its object a vaporizer-condenser of the mentioned type, characterized in that the chamber is located outside of any distillation column and is adapted to contain a bath of liquid to be vaporized.
According to particular embodiments, the vaporizer-condenser can comprise one or several of the following characteristics, taken alone or according to any possible technical combination:
said or each chamber is formed such that in use, a bath of liquid can surround at least the lower part of the heat exchange body and preferably overflow the upper edge of the latter;
said or each heat exchange body comprises several juxtaposed heat exchange blocks along the longitudinal axis of the central section of the corresponding confinement chamber;
said or each heat exchange body comprises inlet and outlet connections for fluids, these connections communicate with flat passages of the heat exchange body and are assigned pair-wise to a fluid, the connections of each pair of inlet and outlet connections assigned to a same fluid being disposed substantially symmetrically relative to a longitudinal and median plane of said heat exchange body;
said or each of said heat exchange bodies comprises at least one inlet collector and an outlet collector connected respectively to a pair of inlet and outlet connections assigned to a same fluid;
for said or each heat exchange body, the outlet or inlet collector or collectors are supported by a same region, particularly the longitudinal end, of the corresponding confinement chamber;
for said or each confinement chamber, the central section has a general shape of revolution about its longitudinal axis and preferably the chamber is cylindrical;
said or each confinement chamber is or is not delimited, at the level of its central section, in part by the corresponding heat exchange body;
said heat exchange body comprises inlet and outlet connections for fluids communicating with the flat passages of said heat exchange body, and these connections are disposed outside said confinement chamber;
said or each heat exchange body comprises inlet connection for a gas communicating with passages of the heat exchange body, said heat exchange body comprising means for introduction into these passages of the condensed gas present in said inlet connections;
the flat passages of the at least one body are oriented transversely relative to the longitudinal direction of the confinement chamber.
the vaporizer comprising at least two bodies, one having flat passages or oriented transversely relative to the longitudinal direction of its confinement chamber and the other having flat passages oriented parallel relative to the longitudinal direction of its confinement chamber.
The invention moreover has for its object an installation for the distillation of air, characterized in that it comprises a vaporizer-condenser as defined above, and in that the longitudinal axis of the central section of said or each confinement chamber of the vaporizer-condenser is substantially horizontal.
xe2x80x9cSubstantially horizontalxe2x80x9d means xe2x80x9chorizontal or having departures up to 30xc2x0, preferably 10xc2x0, from the horizontalxe2x80x9d.
Obviously, the heat exchanger within the chamber must remain horizontal so that its operation will be ensured.
According to modifications:
the installation comprises a medium pressure column, a low pressure column, nitrogen from the head of the medium pressure column and oxygen from the bottom of the low pressure column being placed in heat exchange relation by the vaporizer-condenser;
said or each confinement chamber is disposed beside medium pressure and low pressure columns;
at least a portion of the vaporizer-condenser is disposed at a level intermediate those of the bottom of the low pressure column and the top of the medium pressure column;
the chamber contains a liquid oxygen bath in which the body is submerged in use and
the installation comprises a principal heat exchange line to cool the air to be distilled, and the vaporizer-condenser surmounts the principal heat exchange line, the vaporizer-condenser and the principal heat exchange line having if desired parallel axes.